Optimization

Once risk and issue areas are identified and their root cause (mode shapes and frequency), you can setup an optimization solver deck to get solution proposals. Problems are categorized as systematic issues and non-systematic issues.

Systematic Issues

Systematic issues are:
  • Problems that will appear consistently across the population of products, independently of tolerance variations or small changes in the structure.
  • Identified to be profound design issues that require change of mounting strategy.
The advantages of choosing topology or systematic optimization are:
  • OptiStruct's design-synthesis technology uses the topology optimization approach to generate innovative concept design proposals. OptiStruct generates an optimal design proposal for the connectors layout of the design based on user-defined design space and design targets.
  • In SnRD Modal Frequency (MFREQ) Response analysis is used as the optimization load case with an objective of minimizing the modal relative displacement across the selected E-Line.
  • SnRD Optimization module, automatically converts the time domain excitations to frequency domain for creating the MFREQ loadcase. Amplitude and phase are considered.
  • The design variable for Topology optimization is the CBAR element connecting the Main and Secondary components.
  • Optimization can be done for the response at single frequency or for a band of frequencies.

Non-systematic Issues

Non-systematic issues are:
  • Problems that will appear in a portion of the population of products. They highly depend on tolerances and variations, and are often not detected during physical validation due to a lack of representative tested population.
  • Typical root cause is a lack of local stiffness.

On the analysis side, the optimization input deck is generated automatically with all required solver cards. The solution type is a MFREQ analysis, where the objective is to minimize relative modal displacement at one or multiple locations for a specific frequency, or a frequency range you define. In the case of the 2D free-size optimization, you can define the allowable thickness range for the selected parts.

Advantages of choosing free size or Non Systematic optimization:
  • Free-size optimization (targeting Non-Systematic issues) in OptiStruct optimizes the thickness of every element in the design space to generate an optimized thickness distribution in the structure, for the given objective under given constraints.
  • In SnRD MFREQ Response analysis is used as the optimization load case with an objective of minimizing the modal relative displacement across the selected E-Line.
  • SnRD Optimization module automatically converts the time domain excitations to frequency domain for creating the MFREQ loadcase. Amplitude and phase are considered.
  • The design variable for free-size optimization is the thickness of the shell elements on the surfaces.
  • Optimization can be done for the response at single frequency or for a band of frequencies.